Lie Algebras of Classical Type W. MillsG. Seligman Indiana University Mathematics Journal 1957 text pdf 10.1512/iumj.1957.6.56024 10.1512/iumj.1957.6.56024 en Indiana Univ. Math. J. 6 (1957) 519 - 548 state-of-the-art mathematics http://iumj.org/access/